BasKet Archive file formatThe BasKet file format (.baskets) is a structure which wraps a compressed tar and a preview image. The latest archive format version is 0.6.1.
The archive file is divided into the structures: file header, preview image header, a preview image (.png), archive header, and a gunzipped tar archive (.tar.gz) containing a baskets file tree as illustrated in the following sketch
The file header is a short structure, consisting of lines of strings, the file declarator, and the format version
The first 17 bytes contain the literal string BasKetNP:archive followed by a new line feed symbol (0x0A) in ISO-8859-1 encoding.
The second string is a literal string version:0.6.1 followed by a line feed symbol (0x0A) in ISO-8859-1 encoding.
An example:
BasKetNP:archive version:0.6.1
Currently, the basket archive file contains a preview file which is derived from the first basket's content.
Directly following the file header, a literal string preview*:<size> in ISO-8859-1 encoding, again followed by a line feed symbol. The parameter <size> is a string of decimal numbers. It declares the size in bytes of the preview image. <size> is of type unsigned long.
An example:
preview*:12000
The preview image is of type .png. Its size is specified by the preview image header. The preview image file is inserted as file stream, and directly follows the preview image header.
Just like for the preview image file, the content archive is preceded by a string specifying its size. That string directly follows the file stream of the archive.
That string must be archive*:<size> followed by a line feed symbol, in ISO-8869-1 encoding. The parameter <size> is a unsigned long integer in string format.
An example:
archive*:1245000
The content archive contains the BasKet file tree compressed in to a gzipped tar archive (.tar.gz). Its size is specified by the content header.
The following table shows key parts of the basket archive file content. The left column specifies the offset in the file stream. The center column gives the byte stream at the current offset in hexadecimal format. The right column shows printable characters within the file stream at the current offset.
